Short answer: With current technology, a one-way trip from Earth to Mars typically takes about 6 to 9 months, depending on orbital positions and the propulsion system used. Travel times can vary widely from roughly 3 to 5 months for some optimized mission designs, to about 9 months for conventional Hohmann-transfer-type trajectories, and could be shorter or longer with future propulsion advances.

Key factors that determine travel time

• Orbital alignment: The closest, most energy-efficient windows (often called Hohmann-transfer windows) occur roughly every 26 months when Earth and Mars line up favorably. This significantly influences mission duration.

• Trajectory type:
  • Conventional chemical propulsion using a Hohmann transfer typically yields around 6–9 months travel time.

* Optimized or alternative propulsion concepts (e.g., higher-energy trajectories) could shave time to the 3–5 month range in some analyses, though these are less common today.

• Speed and propulsion: The spacecraft’s departure velocity (C3) and the propulsion system largely determine transit duration; more powerful or advanced propulsion could reduce time but comes with trade-offs.

Typical mission examples

• NASA’s Perseverance rover: launched July 2020, landed February 2021 — about 7 months in transit. This is representative of a standard robotic search-and-analysis mission profile.

• Spaceflight industry estimates for crewed or cargo missions generally place nominal crewed transfers in the 6–9 month range under today’s technology, with potential future reductions under new propulsion research.

Human factors and mission design

• A longer or shorter transit affects life-support, food, and psychological considerations for crewed missions, as well as thermal and radiation exposure. Mission planners weigh these factors along with travel time when designing interplanetary missions.

If you’d like, I can tailor these ranges to a specific mission profile (robotic vs crewed, chemical vs conceptual advanced propulsion) and lay out a rough timeline with the major milestones.